Patent application title: Device for Operating an Electrical User on a Motor Vehicle

Abstract:

The invention relates to a device (1), for operating an electrical user
(10), in particular an electric motor on a motor vehicle (2). The device
(1) comprises an electrical controller (4), which can be connected to an
earth voltage (15), at least one electrical user (10), at least one
electrical line (8, 12), connecting the user(s) (10) to the electronic
controller (4) and at least one earth connection (14), connecting the
electrical user(s) (10) to the earth voltage (15) via the controller (4).
Said device can be used to operate for example, hatches, sliding doors
and doors with electric motors.

Claims:

1. An apparatus for the operation of at least one electrical load in a
motor vehicle, comprising at leastone electronic control unit which can
be connected to a ground potential,at least one electrical load,at least
one electrical line which connects the at least one load to the
electronic control unit,at least one ground connection which connects the
at least one electrical load to the ground potential via the electronic
control unit.

2. The apparatus as claimed in claim 1, wherein the at least one
electrical load comprises at least one electric motor, wherein also the
at least one electric motor preferably has a housing and at least two
electrical terminals, in which a respective electrical line is connected
to an electrical terminal and the, particularly one, ground connection is
connected to the housing.

3. The apparatus as claimed in claim 1, wherein the at least one
electrical line and the at least one ground connection determine a
connection path and are in contact with one another for the majority of
the connection path, the majority preferably being at least 70% or even
at least 90% of the connection path.

4. The apparatus as claimed in claim 1, wherein the at least one
electrical line is not entwined with the at least one ground connection.

5. The apparatus as claimed in claim 1, wherein a plurality of electrical
lines are provided, wherein a ground connection is positioned centrally
with respect to the plurality of electrical lines.

6. The apparatus as claimed in claim 5, wherein two electrical lines are
arranged in one plane, and a single ground connection is positioned in
between.

7. The use of the apparatus as claimed in claim 1 for moving a flap on a
motor vehicle.

8. A motor vehicle having the apparatus as claimed in claim 1, wherein the
at least one electrical load is mounted on a bodywork element,
particularly one coated so as to be electrically insulated, of the motor
vehicle.

9. The motor vehicle as claimed in claim 8, wherein an electrical load has
an electric motor for operating a flap on the motor vehicle.

Description:

[0001]The present invention relates to an apparatus for the operation of
an electrical load, particularly an electric motor, in a motor vehicle.
The apparatus can be used to move flaps, sliding doors and doors, for
example, by electric motors.

[0002]The development of electronic assemblies shows that information is
being processed with ever lower power levels, that the functionality for
said electronic assemblies is continually increasing and that at the same
time the size thereof is constantly decreasing. However, this development
also results in the operation of electronic assemblies being able to be
disrupted more easily by electromagnetic radiated interference. To ensure
a sufficient level of reliability and the operation of such assemblies,
electromagnetic compatibility (EMC) plays an important part. Improved
electromagnetic compatibility of components can be achieved, by way of
example, by reducing the power of radiated interference and/or improving
the shielding of sensitive electronic assemblies against electromagnetic
interference.

[0003]If an electronic assembly is connected to an electrical load by
means of electrical lines, electromagnetic interference originating from
the electronic assembly can reach the electrical load via the lines. The
electrical load and the electrical lines can then act as an antenna and
emit the electromagnetic interference into the environment. If the
electrical load is also connected to a door or a flap on a motor vehicle,
for example, it is also possible for these parts of the motor vehicle to
favor the emission of the electromagnetic interference.

[0004]An electronic component on its own will emit only very little
interference when suitable shielding is used. If an electronic component
is connected to an electrical load by means of electrical conductors,
however, electromagnetic interference emissions from the electronic
component cause interference voltages, particularly high-frequency
common-mode interference voltages, and/or interference currents,
particularly high-frequency common-mode interference currents, in the
supply lines for the electrical load. The electrical load, the supply
lines and the metal elements to which the load is connected can then act
as an antenna and emit the electromagnetic interference to the
environment. The intensity of this effect is also dependent on the
frequency of the interference voltages.

[0005]Against this background, it is an object of the present invention to
specify an apparatus which at least partially solves the problems
outlined with reference to the prior art, the aim being particularly to
specify an apparatus which connects an electronic assembly to an
electrical load by means of electrical lines such that no or very little
radiated interference occurs. In addition, the apparatus is intended to
be inexpensive and flexibly positionable in the vehicle and to provide
the option of subsequently improving existing systems (retrofitting).

[0006]These objects are achieved by means of an apparatus in accordance
with the features of the independent claims. Further advantageous
refinements are specified in the respective dependent claims. It should
be pointed out that the features presented individually in the patent
claims can be combined with one another in any manner which makes
technological sense, and exhibit further refinements of the invention.
The description, particularly in conjunction with the figures, provides
advice of further preferred refinements of the invention.

[0007]Therefore, the inventive apparatus for the operation of at least one
electrical load in a motor vehicle comprises at least: [0008]one
electronic control unit which can be connected to a ground potential,
[0009]at least one electrical load, [0010]at least one electrical line
which connects the at least one electrical load to the electronic control
unit, [0011]at least one ground connection which connects the at least
one electrical load to the ground potential via the electronic control
unit.

[0012]Examples of suitable electrical loads are an electrical drive or an
electrical switch, a radio, a loudspeaker box, an antenna or a similar
electrical load in a motor vehicle which is connected by means of
electrical lines to an electronic assembly, particularly a controller
and/or regulatory unit. The connection of the electrical load to a ground
connection by means of the control unit for the ground potential serves
to avoid and/or reduce electromagnetic radiated interference. If the
electronic assembly emits electromagnetic interference, said interference
can cause an interference current, particularly a high-frequency
common-mode current, in the supply lines for the electrical load. These
interference currents can then be emitted by the load in the form of
electromagnetic radiated interference. A connection between the
electrical load and the ground potential discharges the interference
currents to ground potential and can thus reduce the radiated
interference.

[0013]Ground potential particularly means an electrical potential in an
article. In the case of a motor vehicle, the bodywork may be an article
at ground potential, for example. The electrical connection of an article
at ground potential to another component, particularly a control unit, or
an electrical load is made by means of a ground connection which
electrically conductively connects the component to a ground potential or
to an article which is at ground potential.

[0014]The electrical lines can be used to supply an electrical load with
electrical power, for example, and/or also to transmit electrical
signals. If the electrical load is an electric motor, the electric motor
can be provided with a supply voltage via an electronic control unit,
particularly an electronic controller. The electric motor can be actuated
by the electrical control unit particularly using pulse width modulation
(PWM).

[0015]Usually, the electrical lines (or at least one of them) and the
ground connection are produced with a different cross section, the ground
connection regularly having a larger cross section--but this is not
absolutely necessary.

[0016]In line with one development of the invention, an apparatus is
proposed, wherein the at least one electrical load comprises at least one
electric motor, wherein also the at least one electric motor preferably
has a housing and at least two electrical terminals, in which a
respective electrical line is connected to an electrical terminal and
the, particularly one, ground connection is connected to the housing.

[0017]The interference currents flowing in the electrical lines can reach
the housing and be emitted therefrom by means of capacitive coupling. The
electromagnetic interference radiated from the housing is now reduced by
connecting the housing of the motor, particularly the metal or
electrically conductive parts of the housing, to the electronic control
unit by means of the ground connection, and said control unit being
connected to the ground potential.

[0018]The position of the electrical lines relative to the ground
connection has an effect on the magnitude of the radiated interference
which occurs. Positions for the lines with respect to the ground
connection which have low radiated interference are described in the
subsequent developments of the invention.

[0019]In line with one development of the invention, the at least one
electrical line and the at least one ground connection, which determine a
connection path, are in contact with one another for the majority of the
connection path, the majority preferably being at least 70% or even at
least 90% of the connection path.

[0020]In this case, the connection path means the path from the electrical
load via a ground connection or via an electrical line to the electronic
control unit. The contact between the ground connection and an electrical
line also covers the electrical line being no further than 5 cm (or even
just 2 cm and possibly no more than 0.8 cm), for example, away from the
ground connection (or these being in direct contact with one another).
The contact between the electrical lines and the ground connection can
also be achieved by virtue of the electrical lines being bonded to the
ground connection, or having a shared sleeve and in this way forming a
cable which encloses the electrical lines and the ground connection. In
this case, the electrical lines and the ground connection are
electrically insulated from one another. This has the advantage that
during installation in the motor vehicle only one cable needs to be laid
and the electrical lines are already in a suitable position relative to
the ground connection.

[0021]In line with a further development of the invention, an apparatus is
proposed in which the at least one electrical line is not intertwined
with the at least one ground connection. Not intertwined also means that
the electrical line is not twisted with the at least one ground
connection or that the electrical line does not twine around the ground
connection, which is frequently the thicker connection in comparison with
the electrical line. Such intertwining can have a disadvantageous effect
on the power of the radiated interference arising from the apparatus.

[0022]In line with a further development of the invention, an apparatus is
proposed in which a plurality of electrical lines are provided, wherein a
ground connection is positioned centrally with respect to the plurality
of electrical lines. Such positioning is distinguished by particularly
low radiated interference powers from the apparatus.

[0023]With three electrical lines and one ground connection, the central
position can mean, for example, that the ground connection between the
first and second or between the second and third lines is arranged in one
plane, or that the lines are situated along an imaginary hollow cylinder
which surrounds the ground connection.

[0024]In line with one development of the invention, an apparatus is
proposed in which two electrical lines are arranged in one plane and a
single ground connection is positioned in between. In other words, this
also means that two electrical lines are situated externally and a ground
connection is positioned in between in contact with both lines, possibly
in the manner of what is known as a ribbon. Such an arrangement allows
simple laying of the lines in the vehicle with simultaneously minimized
radiated interference powers from the apparatus.

[0025]In addition, the invention proposes using the apparatus for moving a
flap on a motor vehicle. The flap may be, in particular, a door, a
sliding door, a sliding roof, a tailgate, a window, the hood, the gas cap
flap or another moving, pivotable and/or movable part of a motor vehicle.
With particular advantage, the present invention can be used in
conjunction with doors and/or sliding doors which have an electronic
control device. By way of example, such control devices may be arranged
in a sliding door and designed to move together therewith.

[0026]In particular, the apparatus described here in line with the
invention can be used in a motor vehicle, wherein the at least one
electrical load can be mounted on a bodywork component, particularly one
coated so as to be electrically insulated, of the motor vehicle. Bodywork
components are considered to be doors, cargo holds, passenger
compartments and the like, for example. Bodywork components coated so as
to be electrically insulated mean lacquered bodywork components, in
particular. If a bodywork component is electrically connected to the
housing of an electrical load and this bodywork component is at ground
potential, the radiated interference caused particularly by the
high-frequency common-mode interference currents on the supply lines for
the electrical load is significantly reduced. If the connection between
the housing and the bodywork component is nonconductive, e.g. caused by
the lacquering, however, or if the bodywork component is not at ground
potential, for example because it is not electrically conductively
connected to the ground potential of another bodywork component, the
radiated interference is not reduced. By contrast, the bodywork component
can then act as an antenna and amplify the radiated interference still
further. This problem is safely solved in this case, which means that
advantages are actually obtained for mass production in automotive
construction.

[0027]The apparatus according to the invention will preferably be used in
a motor vehicle, wherein an electrical load has an electric motor for
operating a flap on the motor vehicle.

[0028]The invention and the technical surroundings will now be explained
in more detail with reference to the figures. It should be pointed out
that the variant embodiments illustrated in the figures do not limit the
invention. Regularly, identical components are provided with the same
reference symbols in all the figures, in which, schematically:

[0029]FIG. 1 shows an inventive apparatus which is connected to a motor
vehicle and is used for operating a flap,

[0030]FIG. 2 shows terminals and connections between an electrical control
unit and an electrical load,

[0031]FIG. 3 shows a measured level profile for long waves in a known
apparatus,

[0032]FIG. 4 shows a measured level profile for long waves in an apparatus
according to the invention,

[0033]FIG. 5 shows a measured level profile for medium waves in a known
apparatus, and

[0034]FIG. 6 shows a measured level profile for medium waves in an
apparatus according to the invention.

[0035]FIG. 1 shows an inventive apparatus 1 which is connected to a motor
vehicle 2 and is used for moving a flap 11. The electronic control unit 4
is connected to the ground potential 15 of the motor vehicle 2 by means
of a second ground connection 3. The electrical load 10 is supplied by
the electrical control unit 4 via the first electrical lines 8 and the
second electrical line 12. The electrical load 10 is connected to the
electrical control unit 4 by means of a first ground line 14. The
electrical load 10 is also mounted on a bodywork component 20 and is used
for removing the flap 11. The interference emitted by the electronic
control unit 4 has previously caused high-frequency common-mode
interference and high-frequency normal-mode interference 6 in the first
electrical line 8 and the second electrical line 12. Particularly the
common-mode interference has then been emitted to the environment. The
apparatus shown here has been able to significantly reduce this emitted
power.

[0036]FIG. 2 schematically shows possible connections and terminals on the
electronic control unit 4 and the electrical load, which in this case is
in the form of an electric motor 16. The first electrical line 8 and the
second electrical line 12 are respectively connected to an electric motor
16 by means of a first electrical terminal 17 and a second electrical
terminal 18. The electric motor 16 is located in a housing 9. The first
electrical line 8 and the second electrical line 12 are notionally
connected to the housing 9 by means of the first capacitive coupling 7
and the second capacitive coupling 13. The arrangement comprising the
electric motor 16, the lines 8 and 12 and the housing 9 therefore has a
parasitic capacitive coupling. The housing 9 is connected to the
electrical control unit 4 by means of a first ground connection 14. The
first ground connection 14 is central with respect to the majority of a
connection path 19 and in a plane 21 between the first electrical line 8
and the second electrical line 12.

[0037]The common-mode interference 5 passes from the first electrical line
8 and the second electrical line 12 capacitively to the housing 9 of the
electric motor 16. From the housing 9, the common-mode interference is
routed via a ground connection 14 to the electronic control unit 4, from
where it is connected to a ground potential 15. This results in
significantly lower radiated interference. The spatial position of the
first ground connection 14, of the first electrical line 8 and of the
second electrical line 12 with respect to one another likewise prompts
reduced radiated interference.

[0038]FIG. 3 and FIG. 4 schematically show the measured level profile 26
for the radiated interference from a known apparatus (FIG. 3) and an
inventive apparatus (FIG. 4) in comparison. In this context, an electric
motor has been examined which is used for opening or pivoting a tailgate
or for opening and closing sliding doors. In this case, the long waves
have been considered first of all, particularly in a range from 150 kHz
to 300 kHz, the frequency range 25 shown extending right through this
range, for example. A first limit 22 is also shown, which illustrates
particularly the maximum tolerance of other components in the motor
vehicle (e.g. 10 dbμV; 10 decibel microvolts). It can be seen that the
peaks or maximum values of the level profile 26 achieve levels for the
radiated interference 24 which reach twice, three times, four times or
even further multiples of this first limit 22 (cf. FIG. 3). FIG. 4, by
contrast, shows the level profile 26 which has been able to be achieved
with an inventive modification, said level profile remaining below the
first limit 22 over the entire frequency range 25 considered here.

[0039]The investigations were also performed in a corresponding manner for
the medium frequency range, particularly in the frequency range 25 from
500 kHz to 1.7 MHz, measurements were performed which are compared in
FIG. 5 and FIG. 6. In this case, a second limit 23 was considered, said
limit being lower, in particular, than the first limit 22--e.g. 6
dBμV. The comparison between these two figures also reveals the
surprisingly positive effect of the inventive apparatus, which was again
tested by way of example for an electric motor for a sliding door of a
motor vehicle. It was also possible to establish that the invention is
particularly effective in the frequency range up to approximately 1.7
MHz, since here particularly all significant EMC maxima are rejected.